Girl 45 mins to Deliver papers on her route however if her brother have a good solid 20 minutes how long would it take if it was just her brother delivering papers

36 minutes

Step-by-step explanation:

It takes 45 mins to deliver paper on her route.

Let X be the amount of time it takes the brother to complete the route.

The brother works at the rate of 1/x route per min

The girl works at the at the rate of 1/45 route per min

Girl and brother working together works at rate of 1/20 route per min

1/x + 1/45 = 1/20

Multiply through by 180x

180 + 4x = 9x

4x - 9x = -180

-5x = -180

x = -180 / -5

x = 36 mins.

It takes the brother 36 minutes to complete route alone.